Learning more about XP
About
Xeroderma Pigmentosum is a autosomal recessive disease. That means it can only affect people that carrier the disease or have both copies of the gene. It also means only 1/4 children have it when two carriers reproduce. XP effects the 9th chromosome and is a deletion mutation. It alters the XPA protein making it unable to fix cells harmed from UV light. This cell sensitivty and disabilty is what causes the visual changes in the skin.
Apperence
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Most people who are exposed to UV light will suffer visual changes stemming from the damage skin cells. This is what produces the freckles that are the most common symptom.
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Most people who have it will develop some type of eye or skin cancer which is why most will die from a young age.
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In the second stage people will develop thinning skin which will make web-like blood spots appear.